Add GC9A01 Driver (#452)

* Added driver for gc9a01 round display and example code

gc9a01/registers.go

@@ -0,0 +1,65 @@
+package gc9a01
+
+// Registers
+const (
+	NOP        = 0x00
+	SWRESET    = 0x01
+	RDDIDIF    = 0x04
+	RDDST      = 0x09
+	SLPIN      = 0x10
+	SLPOUT     = 0x11
+	PTLON      = 0x12
+	NORON      = 0x13
+	INVOFF     = 0x20
+	INVON      = 0x21
+	DISPOFF    = 0x28
+	DISPON     = 0x29
+	CASET      = 0x2A
+	RASET      = 0x2B
+	RAMWR      = 0x2C
+	PTLAR      = 0x30
+	VSCRDEF    = 0x33
+	TEOFF      = 0x34
+	TEON       = 0x35
+	MADCTR     = 0x36
+	VSCRSADD   = 0x37
+	IDMOFF     = 0x38
+	IDMON      = 0x39
+	COLMOD     = 0x3A
+	RMEMCON    = 0x3C
+	STTRSCL    = 0x44
+	GTSCL      = 0x45
+	WRDISBV    = 0x51
+	WRCTRLD    = 0x51
+	MADCTL_MY  = 0x80
+	MADCTL_MX  = 0x40
+	MADCTL_MV  = 0x20
+	MADCTL_ML  = 0x10
+	MADCTL_RGB = 0x00
+	MADCTL_BGR = 0x08
+	MADCTL_MH  = 0x04
+	RDID1      = 0xDA
+	RDID2      = 0xDB
+	RDID3      = 0xDC
+	RGBICTR    = 0xB0
+	BLPCHCTRL  = 0xB5
+	DISFNCTL   = 0xB6
+	TECTL      = 0xBA
+	INTCTL     = 0xBA
+	FRMCTL     = 0xE8
+	SPICTL     = 0xE9
+	PWCTR1     = 0xC1
+	PWCTR2     = 0xC2
+	PWCTR3     = 0xC3
+	PWCTR4     = 0xC4
+	PWCTR7     = 0xC7
+	INTEN1     = 0xFE
+	INTEN2     = 0xEF
+	GMSET1     = 0xF0
+	GMSET2     = 0xF1
+	GMSET3     = 0xF2
+	GMSET4     = 0xF3
+
+	HORIZONTAL Orientation = 0
+	VERTICAL   Orientation = 1
+)